Lubricating greases containing borate



United States Patent Office 3,125,525 Patented Mar. 17, 1964 3,125,525LUBRICATIN G GREASES CONTAINING BORATE ESTER-AMINE COMPLEXES William R.Siegart, Wappingers Falls, Clemence J. Henry, Newburgh, and Norman R.Odell and Fred C. Toettcher, Fishkill, N.Y., assignors to Texaco Inc.,New York, N.Y., a corporation of Delaware No Drawing. Filed Jan. 17,1961, Ser. No. 83,183

14 Claims. (Cl. 252-3345) This invention relates to lubricating greasesand to a novel class of additives therefor. More particularly, itrelates to hydroxy fatty acid soap thickened greases containingcompounds formed between borate esters and high molecular weightaliphatic amines.

The compounds which are employed as grease additives in accordance withthis invention are association complexes which are formed by reactingaliphatic amines of the class consisting of monoamines containing atleast 6 carbon atoms per molecule and diamines, with boric acid esterscontaining 13 --OR or SR groups attached to a' boron atom, where R is ahydrocarbon group or substituted hydrocarbon group. These borateesteramine complexes are disclosed and claimed in copending co-ownedapplication Serial No. 59,180, of E. L. Kay and E. C. Knowles, filedSeptember 29, 1960, as additives for liquid lubricants such as acombination transmission-rear axle automotive lubricant, wherein theyimpart improved anti-wear properties under the conditions of hypoid gearlubrication as well as detergency and other improved properties for thistype of service.

We have found, in accordance with the present invention, that increaseddropping points and other advantages, including improved waterresistance properties, are obtained in hydroxy fatty acid soap thickenedgreases by employing therein minor amounts of compounds of the aboveclass. A particularly valuable application of this invention is found inthe production of hydroxy fatty acid soap thickened greases containingfatty type extreme pressure agents, which ordinarily strongly degradethe water absorption properties of such greases. Lubricating greasesrepresenting a preferred embodiment of this invention, having acombination of high dropping points, good extreme pressure propertiesand very satisfactory water resistance properties, are obtained byemploying borate ester-amine complexes in lithium hydroxy fatty acidsoap thickened greases containing sulfurized fatty oils.

The above advantages obtained by employing the borate ester-aminecomplexes in hydroxy fatty acid soap thickened greases were entirelyunexpected on the basis of the experience with these compounds employedin conventional fatty acid soap thickened greases, wherein no advantageswere obtained. While we do not intend to be limited by any particulartheory, it appears on the basis of infrared analyses and other evidencethat a stable coordinated compound is formed by electron sharing betweenthe boron atom of the borate ester compound and the hydroxy group of thehydroxy fatty acid soap, which accounts for the diiference in the effectof the borate ester compounds in hydroxy fatty acid soap thickenedgreases and in conventional fatty acid soap thickened greases.

The borate esters which are employed for forming these complexes arecompounds of the class represented by the formulas:

wherein R is a hydrocarbon or substituted hydrocarbon group, R ishydrogen, a hydrocarbon group or substituted hydrocarbon group, X isoxygen or sulfur, n is a whole number from 0 to 2, inclusive, m is awhole number from 1 to 3, inclusive, the sum of n and in being 3, n is awhole number from O to 3, inclusive, m is a whole number from 1 to 4,inclusive, the sum of n and m being 4, the compound containing at leastone hydrocarbon or substituted hydrocarbon group represented by R or R.Hydrocarbon groups represented by R and R include alkyl, aryl, alkaryland aralkyl groups, and substituted derivatives thereof containingsubstituents such as hydroxy, alkoxy, phenoxy, nitro and amine groups,halogens, etc. The preferred compounds are those wherein n and 12' equalzero, in being 3 and m being 4, and wherein all of the groupsrepresented by R are hydrocarbon or substituted hydrocarbon groups,preferably containing at least 3 carbon atoms. Particularly preferredcompounds are those wherein at least one group represented by R is aphenyl group having an electronegative substituent such as a halogenatom or nitro group in a position para to the ester linkage.

Examples of suitable compounds of the above clas include the following:

Particularly suitable compounds are di-p-chlorophenylmono-nonylphenylborate and di-p-chlorophenyl-mono- (alkyl-o-cresyl) borate, wherein thealkyl group contains about 430 carbon atoms.

The aliphatic amines which are employed to form the borate ester adductsor association complexes are compounds of the class comprisingmonoamines containing at least six aliphatic carbon atoms and diamines,wherein the amine groups may be primary, secondary or tertiary aminegroups. Examples of suitable amines include dodecyl amine, tertiarytetradecyl amine, tertiary undecyl amine, secondary dibutyl amine,octylamine, hexadecylamine, ethylene diamine, hexane diamine, etc. Thepreferred compounds are monoamines containing from about 8 to about 26aliphatic carbon atoms per molecule, particularly suitable compoundsbeing primary amines wherein the alkyl group is a tertiary alkyl group.

Formation of the borate ester-amine complexes takes place readily over awide range of conditions. The complex may be prepared by merely mixingtogether the borate ester and amine in the reacting proportions at roomtemperature or at moderately increased temperatures in the presence orabsence of a solvent. The preparation may also be carried out byreacting together boric acid and alcohol together with the amine in anorganic solvent such as benzene, toluene, etc. The borate ester andamine are usually reacted in a 1:1 mol ratio. However, complexescontaining reduced amounts of amine, such as borate ester-amine molratios of :5 to 10:1 may be employed in some cases, particularly wherethere are severe copper anti-corrosiveness requirements.

The lubricating greases to which this invention relates are thosecontaining metal soaps of high molecular weight hydroxy fatty acids insufiicient proportions to provide at least a substantial thickeningeffect. The metal component may be any metal which is suitable forforming soaps employed as thickening agents in lubricating greasesgenerally, including sodium, potassium, lithium, calcium, barium,strontium, aluminum, manganese, zinc, etc. The alkali metals andalkaline earth metals comprise a preferred class of metals for thispurpose. The hydroxy fatty acid soap will usually be present in thecomposition in amounts from about 3 to about percent by weight, althoughsomewhat smaller or larger amounts are also suitable, such as amounts aslow as about 2 percent by weight and as high as about percent by weightof the composition.

The borate ester-amine complexes are ordinarily employed in theselubricating greases in amounts in about the range 01-10 percent byweight, although somewhat larger or smaller amounts may be employed ifdesired. They are most suitably employed in amounts in about the range0.5-5 percent by weight of the grease composition.

Suitable soap forming acid materials which may be employed in theproduction of these greases include hydroxy fatty acids containing fromabout 12 to about 24 carbon atoms per molecule and one or more hydroxygroups separated from the carboxylic group by at least one carbon atom,and the glycerides and other esters of such acids. The preferred acidsare substantially saturated acids containing from about 16 to about 22carbon atoms and one or two hydroxy groups per molecule. Such materialsmay be obtained from naturally occurring glycerides, by hydroxylation offatty acids, by hydrogenation of ricinoleic acid or castor oil, orotherwise by processes such as the catalytic oxidation of hydrocarbonoils and waxes which have been extracted and fractionated to the desiredmolecular range. Mixtures of hydroxy acids together with unsubstitutedfatty acids may be very suitably employed, wherein the hydroxy fattyacid comprises at least about one third of the fatty acid mixture.

Lubricating oils employed in the greases include conventional mineraloils and synthetic oils, such as high molecular weight ethers, esters,silicones, etc. mineral oils include both paraflinic and naphthenic oilsand blends thereof, having viscosities in the range from about secondsSaybolt Universal at F. to about 225 seconds Saybolt Universal at 210 F.A particularly suitable class of synthetic lubricating oils comprisessynthetic dicarboxylic acid esters, such as di-2- ethylhexyl sebacate,(di-secondary amyl) sebacate, di-2- ethylhexyl azelate, etc. andpolymers obtained by condensing dicarboxylic acids with glycols asdisclosed in U.S. 2,628,974, as well as the sulfur analogs of suchesters. Other synthetic oils which may be employed in accordance withthis invention include the silicone polymers, including dialkyl siliconepolymers such as dimethyl silicone polymer, diethyl silicones and mixedaryl alkyl silicone polymers such as phenyl methyl silicone polymer,having viscosities in the lubricating oil viscosity range.

The sulfurized fatty oils which are employed in the greases representinga preferred embodiment of this invention may be any sulfurized naturalor synthetically obtained fatty materials such as have been employedheretofore as extreme pressure additives in lubricating compositions,including, for example, products obtained by sulfurizing castor oil,lard oil, sperm oil, corn oil, fish oil, or the like. A suitablematerial of this character is Suitable sulfurized lard oil containingfrom about 5 to 12 percent by weight of sulfur, obtained by heating No.1 lard oil with about 10 to 15 percent of sulfur at a temperature above300 F., and preferably in about the range 350- 400 F., for a suflicienttime to obtain a homogeneous product. A particularly preferred materialof this type is sulfurized sperm oil, containing from about 5 to 15percent of sulfur. The composition may very suitably contain from about0.5 to 15 percent, and preferably from about 1 to 10 percent by weight,of the sulfurized fatty oil.

The lubricating greases of this invention may also contain otheradditives of various types such as are commonly employed in lubricatinggreases, such as other extreme pressure agents, anti-corrosives,anti-oxidants, etc., as well as different thickening agents, such asother soaps of various types and finely divided solids having greaseforming properties.

The grease preparation may be carried out in any suitable manner. Theborate ester-amine complex may be added either during the greasepreparation or it may be incorporated into the previously preparedgrease by heating a mixture of the grease and a borate ester-aminecomplex at a mildly elevated temperature such as about F. with stirring,preferably followed by milling. It is conveniently added during thegrease preparation when the mixture has cooled below about 200 F.

The following examples are given for the purpose of more fullydisclosing the invention.

EXAMPLE I A lubricating grease having the following composition inpercent by weight:

Lithium 12-hydroxystearate 7.8 Free LiOH 0.2 Borate ester-amine complex3.0 Lubricating oil Remainder The lubricating oil is a mixture in a 3:1ratio by weight, respectively, of Z-ethylhexyl sebacate and a highlyrcfined paraflinic distillate oil having a Saybolt Universal viscosityof about 100 seconds at 100 F.

The borate ester is an association complex obtained by reacting a borateester with a high molecular weight amine in a mol ratio of 1:1. Theamine employed is suitably a commercial material sold by Rohm & Haasunder the trade name of Primene 81-R consisting of tertiary alkylprimary amines in the range from C12H25NH2 to C15H31NH2.

Following is a detailed description of the preparation of one of theseborate ester-amine complexes: 257 grams (2 mols) of p-chlorophenol, 61.8grams (1 mol) of boric acid and 200 ml. of isopropyl benzene werecharged to a 1 liter, three-necked flask equipped with stirrer,condenser and Barrett type distilling receiver, and the mixture heatedunder reflux for 2.16 hours until 36 ml. (2 mols) of water were removed.At this point 220 grams (1 mol) of nonylphenol were added and thesolution was refluxed for an additional 26.16 hours until 18 ml. ofwater were obtained. The solvent was removed under reduced pressure and191 grams (1 equivalent based on Rohm & Haas data) of Primene 81R wereadded slowly over a period of 40 minutes, a temperature rise of about 34C. occurring in the reaction mixture indicative of adduct formation. Theproduct was stirred for an additional 2.16 hours and then removed fromthe flask; the product was a clear yellow viscous liquid, obtained in a99+ percent yield.

The grease preparation is carried out by saponifying Hydrofol acids 200with excess lithium hydroxide in the presence of a major proportion ofthe mineral oil contained in the grease. The saponification isaccomplished by heating the mixture for about 1 /2 hours at 317 F. Thesaponification mixture is then heated up to 400 F. while adding2-ethylhexyl sebacate and circulating the mixture through a shear valveat 75 lbs. pressure drop while the mixture is maintained at 400 F. Themixture is cooled to 200 F. during about 2 /2 hours While additionalamounts of mineral oil and Z-ethylhexyl sebacate are added. The greaseis finally drawn and finished by milling in a Premier colloid mill. Theborate esteramine complex is incorporated into the base grease thusobtained by heating a mixture of the grease and the borate ester-aminecomplex in suitable proportions by weight at 150 F. for 30 minutes withstirring and then milling with one pass through a Premier colloid millat 0.002 inch clearance. The grease thus obtained has a smooth butterytexture and very superior lubricating properties generally.

The following table shows the effect of the borate esteramine complexesin increasing the dropping point of the above grease.

Table I Borate ester/ amine Dropping point complex: ASTM, F. None 367Tri-(nonylphenyl) borate/amine 480 Mono-nonylphenyl-di-(p-chlorophenyl)borate/ amine 427 Tri-(p-chlorophenyl) borate/amine 411Di-p-chlorophenyl-mono-l1-(1 carbomethoxy) heptadecyl borate/amine 412Tri-thiophenyl borate/amine 419 Tri-p-tertiary butyl-thiophenylborate/amine 440 In addition to the increased dropping points, amoderate extreme pressure improvement was also obtained with thehalogenated borate ester-amine complexes in the above grease, as shownby the data given in the following table.

Table II Borate ester/ amine complex: Mean Hertz load, kg. None 21Tri-(nonylphenyl) borate/amine 22 Mono-nonylphenyl-di-(p chlorophenyl)borate/ amine 26 Tri-(p-chlorophenyl) borate/ amine 28Di-p-chlorophenyl-mono-l1-(1 carbomethoxy) heptadecyl borate/ amine 31EXAMPLE II A lubricating grease representing a preferred embodiment ofthe invention having the following composition in percent by weight:

Lithium 12-hydroxystearate 6.0 Free LiOI-I 0.1 Glycerine 0.6Diphenylamine 0.6 Sulfurized sperm oil 7.0 Lead naphthenate 1.0 Borateester-amine complex 0.5-3.0 Lubricating oil Remainder The lubricatingoil employed in the above grease is a lend in about a 1:4 weight ratiorespectively of a refined parafiinc distillate oil having a SayboltUniversal viscosity at 100 F. of about 180, and a refined residualfraction from a mixed base crude having a Saybolt Universal viscosity at210 F. of about 105.

The sulfurized sperm oil is a commercial product containing aboutpercent by weight of sulfur, and the lead naphthenate is also acommercial product obtained from petroleum naphthenates.

The grease is prepared substantially as described in Example I,employing hydrogenated castor oil as the saponifiable material andadding the sulfurized sperm oil, lead naphthenate and diphenylamineduring cooling of the grease mixture and when the temperature is about200 F.

Table III below shows the effect of the borate ester- 6 amine complexesin improving the Water absorption properties of the above grease.

Table I I I Concen- Water Penetra- Borate Ester/amine tration, Absorbed,tion of Percent Percent Emulsion None l 220 377 Tri-p-chlorophenylborate/amine 0. 5 326 Do 1. O 45 324 D0 2.0 25 313Di-pehlorophenylmonononylph enyl borate/amine 0. 5 150+ 343 D0 1. 0 35315 D o 2. 0 40 313 Di-para-tort.- butylphenyl-monopnitrophenylborate/amine 1. 0 150+ 324 D0 2. 0 35 313 D inonylphenyl monopentachlorophenyl borate/amine 1. 0 150+ 326 Do 2. 0 40 328 Emulsioninversion.

Table IV below shows the effect of borate ester-amine complexes upon thedropping point of greases containing other metal soaps of hydroxy fattyacids. The borate ester amine complex employed in these greases was thatof monononylphenyl-p-chloropheny1 borate with Primene 81-R. The greaseswere mineral oil base greases containing the thickening agents shown inthe table.

In contrast to the above results obtained with hydroxy fatty acid soapthickened greases, no improvement in dropping point or other advantagewas found with the borate ester-amine complexes in greases thickenedwith conventional fatty acid soaps.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof and only such limitations should be imposed as areindicated in the appended claims.

We claim:

1. A lubricating grease consisting essentially of a lubricating oilthickened to a grease consistency by a metal hydroxy fatty acid soap andcontaining about 0.1-10 percent by weight of a complex of a borate esterand an aliphatic amine selected from the group consisting of monoaminescontaining at least 6 aliphatic carbon atoms per molecule and diamines,said borate ester and said amine being in a mol ratio of 10:1 to 1:1,respectively, and said borate ester being a compound of the classrepresented by the formulas:

wherein R is selected from the class consisting of hydrocarbon groupsand substituted hydrocarbon groups, R is selected from the classconsisting of hydrogen, hydrocar bon groups and substituted hydrocarbongroups, X is selected from the class consisting of oxygen and sulfur, nis a whole number from 0 to 2, inclusive, m is a whole number from 1 to3, inclusive, the sum of n and in being 3, n is a whole number from 0 to3, inclusive, m is a whole number from 1 to 4, inclusive, the sum of nand m being 4, and at least one group represented by R and R Which ispresent in the compound being selected from 7 the class consisting ofhydrocarbon groups and substituted hydrocarbon groups.

2. A lubricating grease according to claim 1 wherein the said aliphaticamine is a tertiary alkyl monoamine containing about 8 to 26 carbonatoms per molecule.

3. A lubricating grease according to claim 1 wherein the said borateester and said amine are in the mol ratio of about 1:1.

4. A lubricating grease according to claim 1 wherein the said borateester is a compound represented by the said formulas wherein n and 12'equal 0 and the groups represented by R are chosen from the classconsisting of hydrocarbon groups and substituted hydrocarbon groups.

5. A lubricating grease according to claim 4 wherein the said borateester contains one phenyl group having a para positioned electronegativesubstituent.

6. A lubricating grease according to claim 1 containing a minorproportion, sufiicient to impart improved extreme pressure properties tothe composition, of a sulfurized fatty oil.

7. A lubricating grease according to claim 1 wherein the metal componentof the said metal hydroxy fatty acid soap is chosen from the groupconsisting of alkali metals and alkaline earth metals.

8. A lubricating grease according to claim 1 wherein the saidlubricating oil is a mineral oil.

9. A lubricating grease according to claim 1 wherein the saidlubricating oil is a dicarboxylic acid ester.

10. A lubricating grease according to claim 1 wherein the said metalfatty acid soap is lithium 12-hydroxystearate.

11. A lubricating grease according to claim 1 wherein the said borateester is di-p-chlorophenyl-mono-nonylphenyl borate.

12. A lubricating composition according to claim 1 wherein the saidborate ester is di-p-chlorophenyl-mono- (alkyl-o-cresyl) borate, saidalkyl group containing about 4-30 carbon atoms.

13. A lubricating grease consisting essentially of a lubricating oilselected from the class consisting of mineral oils and ester oilsthickened to a grease consistency by a metal hydroxy fatty acid soap andcontaining about 0.5- 15 percent by weight of a sulfurized fatty oil andabout 0.55 percent by weight of a complex of a borate ester and analiphatic monoamine containing about 8 to 26 carbon atoms per molecule,said borate ester and said monoamine being in a mol ratio of 10:1 to1:1, respectively, and said borate ester being a compound of the classrepresented by the formulas:

References Cited in the file of this patent UNITED STATES PATENTSBrunstum et a1. Aug. 5, 1958 Ashby et al Nov. 22, 1960

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF A LUBRICATING OILTHICKENED TO A GREASE CONSISTENCY BY A METAL HYDROXY FATTY ACID SOAP ANDCONTAINING ABOUT 0.1-10 PERCENT BY WEIGHT OF A COMPLEX OF A BORATE ESTERAND AN ALIPHATIC AMINE SELECTED FROM THE GROUP CONSISTING OF MONOAMINESCONTAINING AT LEAST 6 ALIPHATIC CARBON ATOMS PER MOLECULE AND DIAMINES,SAID BORATE ESTER AND SAID AMINE BEING IN A MOL RATIO OF 10:1 TO 1:1,RESPECTIVELY, AND SAID BORATE ESTER BEING A COMPOUND OF THE CLASSREPRESENTED BY THE FORMULAS: